This invention relates to coloration of synthetic resins, and more particularly to the provision of weatherable colored resins.
With the ever-expanding areas of use of synthetic resins and especially thermoplastic resins, it is of increasing interest to produce resinous compositions having many types of surface appearance, including coloration. Coloration of resins can be achieved by the use of dyes or pigments. One of the characteristics of pigments is their insolubility in the resin phase, which can lead to adverse consequences including loss of physical properties and loss of surface gloss. It is often preferred, therefore, to employ dyestuffs for coloration since they dissolve in the resin, forming a homogeneous composition which retains the gloss and advantageous physical properties characteristic of the neat resin.
A factor of concern in the coloration of synthetic resins is weatherability. Many dyes and other industrial colorants undergo photodegradation upon exposure to radiation of various wavelengths, often in the ultraviolet region of the spectrum. Thus, the resinous articles containing such colorants suffer a loss of color.
It is of increasing interest, therefore, to produce substantially color-stable resinous articles. It is of further interest to produce articles having a high degree of resistance to weathering and the color changes caused thereby.